1. Field of the Invention
The present invention relates generally to electrically illuminated signs and is more particularly directed to a kit of interacting components whereby signs originally lighted by incandescent bulbs or fluorescent light tubes may be conveniently converted to electroluminescent lighting.
2. Description of the Prior Art
In many public buildings and industrial plants there are provided illuminated cautionary and/or informational signs which define exits, stairwells, fire alarms, equipment-in-use, hazardous areas and the like. Such signs are conventionally illuminated by incandescent bulbs or fluorescent tubes which operate on 110-120 volt AC house current. Incandescent bulb or fluorescent tube lamps are relatively tender objects which are subject to breakage and their service lives are not great, particularly when subject to the vibration that is often experienced in public building and industrial plant setting installations. It is generally desirable, therefore, that the incandescent or fluorescent lighting systems of such signs be replaced by illuminating means which are more energy efficient, which are less prone to breakage and which have longer service lives. In addition, it is also desirable that the replacement illuminating means be operable by a backup battery power supply in the event of house current disruptions.
The closest prior art known to applicant in respect of the present invention is represented by a line of exit signs manufactured and sold by Don Gilbert Industries, Inc., Jonesboro, Arkansas. Said signs are described, in detail, in U.S. Pat. No. 4,682,147, to Norman E. Bowman, dated Jul. 21, 1987, entitled EMERGENCY SIGN. These signs are based upon a light emitting diode (LED) display comprising a multiplicity of LED components arranged and affixed to a display board in the form of the specific information desired to be displayed. Electrical circuitry is provided to receive AC line current and to transform and rectify it to an appropriate DC voltage power output to the LED display. In addition, the power supply circuitry to the LED panel is provided with means by which to sense AC line current power outages and, in response to such outages, to switch the LED panel display to battery power and, in addition, to convert the normally continuously lighted display to a flashing display. While the Bowman emergency signs address many of the problems associated with signs illuminated by incandescent bulbs or fluorescent tubes including, to some extent, the problem of short bulb service life and the capacity to continue operations under power outages, nevertheless they, too, are possessed of certain deficiencies. For instance, the Bowman sign displays are dependent upon a plurality of groups of series wired LED components which must be prepared and affixed to the display at the site of manufacture. Therefore, the specific informational and/or symbolic displays desired by the customer must be prepared at the site of manufacture of the sign and cannot thereafter be altered or supplemented at the installation site. Secondly, the arranging and making of the many electrical connections required between the multiplicity of LED components of the Bowman LED display panels is a relatively time consuming, labor intensive and, therefore, expensive manufacturing task. Moreover, these many electrical connections between the LED components, whether accomplished by printed circuitry or hard wiring, constitute a statistically meaningful population of potential sites for failure during installation and use. Since a plurality of groups of the LED components are required to be connected in series in the Bowman emergency light device, the failure of even a single such connection or LED component invariably affects at least one LED grouping of the display and can, therefore, conceivably render the information displayed by the sign nonsensical or unintelligible. Another problem associated with the Bowman emergency light system resides in the need for employing transformer/rectifier circuitry during normal operations in order to supply the necessary DC voltage to the LED display. Thus, independent electronic elements which are themselves subject to failure during normal operations are necessarily interposed between the LED display and the AC house line current power source. In accordance with the present invention, however, there is provided an illuminated sign conversion kit wherein these aforementioned problems attendant prior art devices have either been substantially completely resolved or at least substantially ameliorated.